Pulse–time-modulated electron cyclotron resonance plasma discharge for highly selective, highly anisotropic, and charge-free etching

Abstract

Highly selective, highly anisotropic, notch-free, and charge-buildup damage-free silicon etching is performed using electron cyclotron resonance (ECR) Cl2 plasma modulated at a pulse timing of a few tens of microseconds. A large quantity of negative ions are produced in the afterglow of the pulse-time-modulated plasma. The decay times of electron density, electron temperature, and sheath potential are considerably reduced. This is attributable to negative-ion generation. Furthermore, the pulse-time-modulated plasma reduces the time averaged sheath potential. As a result of these effects, charged particles in the sheath are drastically modified from the continuous discharge, and they should improve the selective etching in the pulsed ECR plasma and eliminate charge accumulation on the substrate. Additionally, negative-ion generation dramatically improves the plasma potential distributions in the nonuniform ECR plasma. This technique is also suitable for large scaled etching processes.

200-mm-diameter neutral beam source based on inductively coupled plasma etcher and silicon etching

“…14 The rf power was pulse-time modulated so the plasma would contain many negative ions when electronegative gases such as F 2 and Cl 2 are used. 24 It is known that negative ions can give higher neutralization efficiency. 13…”

Application of Pulsed Plasmas for Nanoscale Etching of Semiconductor Devices : A Review

“…. 이후 Samukawa 와 그의 연구팀에 의해 염소가스기반의 펄스 자기 공명 플라즈마(pulsed Cl-based ECR plasmas)를 이 용한 폴리실리콘 식각 연구가 활발히 진행되었다 [40][41][42][43] . 뿐만 아니라 Ahn 등의 연속파와 펄스 플라즈마를 사용한 연구에서도 펄스를 사용하여 식각 진행하였 을 때 노칭현상이 제거됨이 보고되었다 44) .…”

Future TCAD system for nanometer-scale-device manufacturing using plasma etching

“…The plasma density with 10 11 cm -3 spreads widely between both electrodes due to the influence of the spatial trapping of low energy electrons, as compared with that driven by the HF(13.56 MHz)-LF system. In order to overcome plasma damage occurring during the etching process, pulsed operation of a high density plasma source was proposed in order to aim at the control of positive and negative charge flux to the surface during the on/off period [7] B Ion velocity distribution incident on wafer Oxide etching requires a high energy ions incident on the patterned wafer. The energy is distributed between 200 eV to 1000 eV in order to obtain a sufficient etching yield of oxide under the ion assisted mode in feed gases based on Ar and fluorocarbon mixture.…”